The effects of the field emission property in relation to the surface morphology and adhesion force were investigated. The single-wall-nanotube-based cathode was obtained by use of an in-situ arc discharge synthesis method, a screen-printing method and a spray method. The morphologies of the formed emitter layers were very different. The emission stability and uniformity were dramatically improved by employing an in-situ arc discharge synthesis method. In this study, it was confirmed that the current stability and uniformity of the field emission of the cathode depend on the surface morphology and adhesion force of the emitters. The current stability of the field emission device was also studied through an electrical aging process by varying the current and electric field.

A simple method to deposit carbon nanotube films uniformly on large area substrates using an arc discharge method is reported in this paper. The arc discharge method was modified to deposit carbon nanotube films in situ on the substrates. The substrates were scanned several times over the arcing point for a uniform film thickness. Deposition was carried out under variable dc bias conditions at 600 torr of H2 gas. The thickness uniformity of the single-wall carbon nanotube films as characterized by a four-point probe was within 30% deviation. The morphology and crystal quality of the single-wall carbon nanotube film were also characterized by field emission scanning electron microscopy and Raman spectroscopy.

Carbon nanotube (CNT) cathodes were fabricated using nano-sized silver (Ag) powders as a bonding material between the CNTs and cathode electrodes. The effects of the powder size on the sintering behavior, the current density and emission image for CNT cathodes were investigated. As the diameter of the Ag powders decreases to 10 nm, the sintering temperature of the CNT cathode was lowered primarily due to the higher specific surface area of the Ag powders. In this study, it was demonstrated that nano-sized Ag powders can be feasibly used as a bonding material for a screen-printed CNT cathode, yielding a high current density and a uniform emission image.

Single-walled carbon nanotubes (SWNTs)를 320 ℃에서 90분 동안 가열하여 비정질 탄소를 제거하고 남아 있는 금속 촉매를 제거하기 위해 염산에 24시간 처리하였다. 정제된 SWNT 표면에 산화반응을 통해 카복실기를 도입하였으며, 가혹한 환경으로 인해 길이가 짧아진 SWNT를 얻었다. 세정된 실리콘 웨이퍼를 3-aminopropyldiisopropylethoxysilane (3-APDIPES)의 톨루엔 용액에 담가 표면에 3-APDIPES의 자기 조립 단층막을 형성시켰다. SWNT의 카복실기와 3-APDIPES의 아미노기 사이의 산-염기 반응을 통해 생성되는 이온 사이의 정전기적 인력을 이용하여 실리콘 웨이퍼 표면에 SWNT를 배열하였다. Atomic Force Microscopy (AFM) 분석을 통해 반응시간과 농도에 따른 효과를 확인하였고, Transmission Electron Microscopy (TEM)을 이용해 산 처리 시간에 따른 효과를 확인하였다.

Multi-walled carbon nanotube (MWNT)를 황산과 질산의 혼산(3:1)에 넣고 상온에서 ultrasonication 을 가해주어 MWNT의 표면에 산화반응을 통하여 카복실기를 도입하였다. 세정된 실리콘 웨이퍼를 3-aminopropylethoxysilane (3-APDIPES)의 톨루엔 용액에 담그어 실리콘 웨이퍼 표면에 3-APDIPES의 자기 조립 단층막을 형성하였다. 이 과정에서 실리콘 웨이퍼 표면에 형성된 3-APDIPES 자기 조립 단층막의 두께는 8 Å 이며, 이 단층막이 매우 견고하게 실리콘 웨이퍼 표면에 결합되어져 있음을 확인하였다. MWNT의 카복실기와 3-APDIPES의 아미노기 사이의 산-염기 반응을 통하여 생성되는 이온 사이의 정전기적 인력을 이용하여 실리콘 웨이퍼 표면에 MWNT를 배열하였다. 이 때 얻어지는 MWNT의 배향은 수직 배향이 아니라 수평 배향임을 atomic force microscopy (AFM)와 field emission-scanning electron microscopy (FE-SEM) 분석을 통하여 확인하였다.

Amorphous carbon nanotubes were synthesized by a reaction of benzene, ferrocene and Na mixture in a small autoclave at temperatures as low as . The resulting carbon nanotubes were short and straight, but their inner hole was filled with residual products. The addition of quartz to the reacting mixture considerably promoted the formation of carbon nanotubes. A careful examination of powder structure suggested that the nanotubes in this process were mainly formed by surface diffusion of carbon atoms at the surface of solid catalytic particles, not by VLS(vapor-liquid-solid) mechanism.

In-situ processing route was adopted to disperse carbon nanotubes (CNTs) into powders homogeneously. The composite powders with homogeneous dispersion of CNTs could be synthesized by a catalytic route for in-situ formation of CNTs on nano-sized Fe dispersed powders. CNTs/Fe/ nanopowders were densified by spark plasma sintering (SPS). The hardness and bending strength as well as electrical conductivity increased with increasing sintering temperature. However, the electrical conductivity of the composites sintered at above showed decreased value with increasing sintering temperature due to the oxidation of CNTs

Aligned multi-wall carbon nanotubes (MWNTs) were synthesized through the catalytic decomposition of hydrocarbons in a quartz tube reactor. In this study, we investigated the influence of gas flow rate of feedstock on the structure and growth rate of vertically aligned carbon nanotubes produced by the floating catalyst method. As the flow rate of feedstock increased, the nanotube diameter became smaller and the length became longer. Although the growth rate also increased with the raise of flow rate, the optimum flow rate of feedstock existed for the crystallinity of carbon nanotubes.

Multi-walled carbon nanotubes (CNTs) were prepared by microwave plasma chemical vapor deposition (MPCVD) using various combination of binary catalysts and methane precursor. The maximum yield (10.3 %) of CNTs was obtained using a methane-hydrogen-nitrogen mixture with volume ratio of 1:1:2 at 1000 W of microwave power. As the microwave power increased up to 1000 W, the deposition yield of CNTs raised from 4.1 % to 10. 3 %. However, the prepared CNTs at 800 W showed the more crystalline structure than those prepared at 1000 W. The prepared CNTs over different binary catalysts had various structural conformations such as aligned cylinder, bamboo, and nanofibers. The Id/Ig value of CNTs overFe-Fe/Al2O3, Co-Co/Al2O3, and Co-Cu/Al2O3 were in the range of 0.89~0.93. Among the various binary catalysts used, Fe-Co./Al2O3 showed the highest yield.

Although the structure of carbon nanotubes is important factor characterizing its properties, it is very difficult to control the structure of carbon nanotubes (MWNTs) and to predict the range of their diameter, which is the primary factor of MWNTs' physical properties. We tried to control the diameter of MWNTsby governing the feed injection temperature of floating catalyst method. The structure of MWNTs was influenced by the phase change of ferrocene fed as the catalyst,. The carbon nanotubes were very narrow at injection temperatures close to the sublimation pt. of ferrocene, in which most MWNTs had diameters in the range of 20~30 nm. At injection temperatures between the boiling pt. and melting pt. of ferrocene, the diameters became larger and had broad distribution. However, at injection temperatures higher than the boiling pt., the diameters became narrow again and had very uniform distribution.